This article provides a second manifestation of a new tradition by which the editors of Comments on Inorganic Chemistry wish to lead by example, whereby we start publishing original research content that, nonetheless, preserves the Journal’s identity as a niche for “critical discussion of the current literature” of inorganic chemistry. (For the first manifestation, see: Otten, B. M.; Melancon, K. M.; Omary, M. A. “All That Glitters is Not Gold: A Computational Study of Covalent vs Metallophilic Bonding in Bimetallic Complexes of d¹⁰ Metal Centers—A Tribute to Al Cotton on the 10th Anniversary of His Passing,” Comments Inorg. Chem. 2018, 38, 1–35.) Thus, herein we show that a trinuclear copper (I) complex {[3,5-(CF₃)₂Pz]Cu}₃ (henceforth referred to as the “Cu trimer”) can act as a “metal-organic coating” for corrosion protection of aluminum, whereas its silver analogue, {[3,5-(CF₃)₂Pz]Ag}₃ (i.e., the “Ag trimer”), could not. The manuscript was initially submitted to journals that usually publish on “organic coatings” but was rejected on the premise that a metal complex cannot be considered “organic” unless it is incorporated into a polymer. This issue is commented upon herein in the broader context of whether to consider metal complexes “organic,” “inorganic,” “organometallic,” or “metal-organic” materials with manifestations of the use of each classification in the literature. We have found that, upon coating the Cu trimer onto an aluminum (AA 3003) surface, potentiodynamic polarization results in 3.5% NaCl show an increase in corrosion potential (E_corr) by ~ 0.6 V concomitant with a three-order-of-magnitude decrease in corrosion current density (i_corr) from 0.025 µA/cm² for uncoated aluminum to ~ 9.6 × 10^–5 µA/cm² for the Cu trimer-coated surface. With a double coating, the Cu trimer formed a completely insulating surface with no current flow, even at very high potential magnitude and range. Open circuit potential was used to study the stability of the Cu trimer films on the Al surface in the electrolyte solution. Scanning electron microscopy and Fourier-transform infrared spectroscopy techniques were used to characterize the structure of both the Cu trimer powder and Cu trimer film on the aluminum surface before and after the corrosion tests. The hydrophobicity of the Cu trimer coating was determined by using water drop contact angle measurements, which demonstrated an increase from 65° to 137° for the uncoated and coated aluminum, respectively. The thermal stability of the Cu trimer was analyzed using thermogravimetric analysis, giving rise to weight loss resistance up to ~190 °C. The results clearly demonstrate that the Cu trimer layers exhibit superior stability and potential for corrosion protection of aluminum surfaces in corrosive environments. The Ag trimer analogue, meanwhile, failed the “tape test” that the Cu trimer passed to assess the mechanical stability of such “metal-organic” coatings. Density functional theory (DFT) simulations provide insights on this difference upon modeling the interaction of each cyclotrimer molecule (and other analogous ones) with an Al atom on the one hand and contrasting the resulting binding energies with the corresponding dissociation energies of the metallophically-bound crystalline solid form of each trimer. Thus, it was found that Ag trimer models are bound to the Al atom at least as strongly as Cu trimer models are; yet, that bonding is not sufficiently high so as to overcome the argentophilic attraction, whereas it can overcome the cuprophilic attraction. Other explanations are also given to account for trimer interactions with aluminum oxide as well as partial oxidation of only the Cu trimer, which strengthens the interaction with the Al atom.

本文提供了新传统的第二种表现形式，《无机化学评论》的编辑希望以身作则，由此我们开始发表原始研究内容，尽管如此，仍保留了《华尔街日报》作为“对当前问题进行批判性讨论的利基”的身份。无机化学的文献”。（有关第一个表现形式，请参阅：BM的Otten； KM的Melancon；马萨诸塞州的Omary“所有闪闪发光的不是黄金：d ^10个金属中心的双金属配合物中共价键与亲金属键的计算研究-致他的传球的10周年，”评论Inorg。化学。2018，38，1-35）。因此，本文中，我们表明，三核铜（I）络合物{[3,5-（CF ₃）₂ Pz] Cu} ₃（以下称为“ Cu三聚体”）可以作为“有机金属涂层”来保护铝，而其银类似物{[3,5-（CF ₃）₂ Pz] Ag} ₃（即“ Ag三聚体”）不能。该手稿最初提交给通常在“有机涂料”上发表的期刊，但以前提是除非将金属络合物掺入聚合物中，否则该金属络合物不能被视为“有机”。本文在更广泛的上下文中对这个问题进行了评论，即是否将金属配合物视为“有机”，“无机”，“有机金属”或“金属有机”材料，并体现了文献中每种分类法的使用。我们发现，在将铜三聚体涂覆到铝（AA 3003）表面上时，电位动力学极化导致3.5％NaCl的腐蚀电位（E _corr）增加了_〜0.6 V，同时具有三个数量级。腐蚀电流密度降低（i _corr）从无涂层铝的0.025 µA / cm ²到〜9.6×10 ^–5  µA / cm ²用于镀有三聚体的表面。通过双层涂层，Cu三聚体形成了一个完全绝缘的表面，即使在非常高的电位幅度和范围下也没有电流流动。开路电势用于研究电解液中Al表面的Cu三聚体膜的稳定性。在腐蚀试验之前和之后，使用扫描电子显微镜和傅里叶变换红外光谱技术来表征铝表面上的铜三聚体粉末和铜三聚体膜的结构。通过使用水滴接触角测量来确定Cu三聚体涂层的疏水性，这表明未涂覆的铝和涂覆的铝从65°分别增加到137°。使用热重分析法分析了铜三聚体的热稳定性，产生高达〜190°C的抗减肥性。结果清楚地表明，在腐蚀环境中，Cu三聚体层表现出优异的稳定性和对铝表面进行腐蚀防护的潜力。同时，银三聚体类似物未通过铜三聚体通过的“胶带测试”，以评估此类“金属有机”涂层的机械稳定性。密度泛函理论（DFT）模拟一方面通过模拟每个环三聚体分子（和其他类似分子）与Al原子的相互作用，并将所得的结合能与金属相结合的相应解离能进行对比，从而提供了有关此差异的见解每个三聚体的结晶固体形式。因此，发现Ag三聚体模型与Al原子的结合至少与Cu三聚体模型一样牢固。然而，这种键合不够高，不能克服纯银的吸引力，而它可以克服嗜铜的吸引力。还给出了其他解释以说明三聚体与氧化铝的相互作用以及仅铜三聚体的部分氧化，这会增强与Al原子的相互作用。